Abstract: An on-demand type ink jet printing apparatus which prints out data in various forms such as characters and numerals by the combination of dots formed by ink droplets on a sheet of paper. An ink ejection head of the printer includes control electrodes disposed in at least one ink passageway. Ink droplets are formed and caused to fly by electric fields developed in the vicinity of the control electrodes when voltages are applied thereacross. Multiport ink ejection is achieved by the provision of a plurality of ink passageways in the head. The voltage supply to the control electrodes is controllable so that ink droplets may be formed and caused into flight in response to print signals.A channel defining each ink passageway can be shaped easily yet with accuracy utilizing an etching characteristic particular to a specific crystal face.A plurality of acceleration electrodes may be employed to promote desirable flight of ink droplets.

Abstract: An apparatus for removing air from ink which is fed under pressure to a nozzle of an ink ejection head is disclosed. A first solenoid-operated valve is disposed between an ink pressurizing source and the nozzle. Located between the valve and the nozzle is a deaerating unit which has therein a bore for causing air entrained by the ink to surface. An air outlet is formed in an upper portion of the bore and opened and closed by a second solenoid-operated valve. Upon a stop of ink ejection, the first valve is closed (ink supply blocked) while the second valve is opened. Heaters are installed in the bore of the deaerating unit to heat ink inside the bore to a predetermined temperature, so that air in the ink is expanded to become readily separable from the ink.

Abstract: In an ink jet printing apparatus wherein an ink ejection head is loaded on a carriage and, while the carriage moves relative to a sheet of paper, ink droplets are ejected from the head to be charged and deflected to impinge on the sheet of paper, a shape or a position of a conductive member carried on the carriage is varied to develop an electric field which is asymmetrical with respect to a predetermined plane in which charged ink droplets coming out from a charging electrode are to be deflected. The conductive member is constituted by a cover of the carriage, a shield plate, a gutter, a compensating electrode plate, a deflection electrode or the like.

Abstract: A deflection control type ink jet printing apparatus includes a pair of parallel electrodes located downstream of a deflection electrode with respect to an intended direction of ink ejection from an ink ejection head. The electrodes sense a deviation or offset of an actual path of deflection which ink droplets deflected to predetermined one of a plurality of steps follow from a reference path of deflection, which is defined intermediate between the two electrodes. An ink is fed to the head under a pressure which is variable in accordance with the sensed deviation in deflection in order to compensate for the deviation. The two electrodes may be replaced by at least one electrode on which ink droplets deflected to a specific deflection step are to impinge.

Abstract: A deflection detector for an ink jet printer comprises first and second plates made of an insulating material and bonded to each other. The first insulator plate is provided with at least two separate detection electrodes on its one surface and a shield electrode at its other surface, while the second insulator plate is provided with a shield plate on its one surface and bonded to the first plate at the other surface. The first and second plates are formed with aligned slots which also extend throughout the electrodes to pass ink droplets therethrough. The thickness of each detection electrodes corresponds to an interval between successive ink droplets. The deflection detector is positioned such that the plate containing the detection electrodes is substantially perpendicular to a specific reference path for deflection.

Abstract: An ink jet printing apparatus includes a controllable gain charge amplifier circuit adapted to supply a charging electrode with a charge voltage. A reference charge voltage is coupled to the charging electrode to detect an actual position to which charged ink droplets are deflected. The gain of the amplifier circuit is automatically determined so that the actual deflection position coincides with a predetermined reference position. Moreover, the determined gain of the amplifier is automatically adjusted in accordance with charges on preceding droplets to compensate for any distortion of a charge to be deposited on an immediately following droplet attributed to the charges on the preceding droplets.

Abstract: An ink jet printing apparatus uses as its charge detection means a gutter which is made of a conductive material, insulated from collected ink and grounded through a resistor. A charging electrode is supplied with charging voltage pulses for a phase search intermittently at a predetermined period which is at least two times the period of a drive frequency of ink droplets. The resultant voltage appearing across the resistor is amplified and filtered to pick out a pulse signal of the predetermined period. The resistance of the resistor between the gutter and the ground is preselected to be sufficiently smaller than that of the ink.

Abstract: Ink jet deflection is maintained constant regardless of ink temperature by varying the amplitude of pressure oscillation applied to ink in an ejection head (1) as a function of temperature. The pressure oscillation causes the ink to be ejected from the head (1) and separate into droplets. The droplets are charged and electrostatically deflected where it is desired to print a dot. Variation of the amplitude of pressure oscillation changes the shape of the droplets and thereby the amount of charge thereon and the deflection.

Abstract: Considering the fact that a charging voltage and the resultant amount of deflection of an ink droplet are substantially proportional to each other, actual measurement is first made of a charging voltage for causing ink droplets to fly to at least one predetermined deflection position and then, based on the measured voltage, proper charging voltages for driving ink droplets to other deflection positions are computed. Further, more adequate charging voltages are determined taking nozzle compensatory coefficients allotted to individual ink ejection holes of nozzles and/or step compensatory coefficients for individual deflection steps into consideration.

Abstract: Depending upon a position in a dot matrix where an ink drop is to be deposited, the velocity imparted to that ink drop is controlled. The ink drop is charged by a charge electrode impressed with a constant charging voltage and deflected by a pair of electrodes impressed with a constant deflection voltage so as to be placed at an given point.

Abstract: An ink jet printing apparatus causes deflected droplets of ink to move accurately to a predetermined position by detecting the deflection position of the ink droplets a multiplicity of times and varying the amount of deflection on the basis of the detected deflection position. The charging voltage level or the deflecting voltage level which is varied at each adjustment of the deflection amount has a variable amount of variation. As the adjustment of the deflection is repeated many times, the amount of variation of the charge voltage level or that of the deflection voltage level is decreased progressively at a predetermined rate. Ink droplets are charged from the first step over to the last not in a continuous manner according to the order of the steps but by each predetermined group of steps which skip the others.

Abstract: In an ink jet printer of the type wherein an ink jet nozzle continuously ejects the train of ink droplets and only ink droplets which are directed towards a recording surface are electrically charged and deflected by a pair of deflection electrodes so as to dot-form a character, a pair of auxiliary or compensation electrodes are provided in order to eliminate or control the inclination relative to the vertical line of dot-formed characters due to the relative speed between the recording surface and the ink jet nozzle.

Abstract: After adjustment of a charging phase of ink droplets in an ink jet, printing of a line is accomplished by deflecting the ink jet through a number of incremental positions and applying a binary image signal to the ink jet during this time. The proper amount of deflection of the ink jet is adjusted between the above mentioned steps by sweeping the ink jet along an axis. A target electrode (80a) is provided along the axis with an edge thereof intersecting the axis. The ink jet deflection is stopped when an output of an integrating circuit (220) indicates that the ink jet reached the edge. An electric signal is produced indicating an amount of deflection force applied to the ink jet at the time it reaches the edge. A voltage amplification factor for deflecting the ink jet through the incremental positions is set in accordance with the magnitude of the electric signal.

Abstract: In an ink jet printing device wherein when a number of n nozzles are sequentially arranged in the direction of transport of recording paper and spaced apart from each other by a distance corresponding to m characters or ink dots so that when ink dots discharged from each nozzle are arranged in one column on the recording paper in the direction of transport thereof, the adjacent ink dots have a very small spacing, but they are nearly in contact with each other, a modulo-m address counter is stepped so as to store data in a memory while a modulo-n address counter is stepped to read out data. Thus positional deviations between nozzles may be compensated.

Abstract: Depending upon a position in a dot matrix where an ink drop is to be deposited, the velocity imparted to that ink drop is controlled. The ink drop is charged by a charge electrode impressed with a constant charging voltage and deflected by a pair of electrodes impressed with a constant deflection voltage so as to be placed at an given point.

Abstract: Prior to printing, ink drops are ejected from an ink ejection head or nozzle (28) and an amount of deflection is sweepingly varied until the ink drops hit a target (57), thereby providing a reference which compensates for variations in an amount of charge of the ink drops, a deflection voltage and an ink drop velocity. The ink temperature or an ejection pump pressure are sweepingly varied, prior to the deflection sweep operation, until a sensed ink ejection velocity and thereby ink drop mass become equal to a predetermined value to provide a desired printing density or darkness.

Abstract: A voltage is applied to a plurality of electromechanical transducers mounted on a plurality of nozzles, respectively, so that a meniscus may be formed at the nozzle tip. One or more opposing electrodes or rear transducers are disposed in opposed relationship with a predetermined number of nozzles, respectively, the number of the opposing electrodes or rear transducers being less than that of the nozzles. When one of the opposing electrodes or rear transducers which is in opposed relationship with the nozzle whose transducer is applied with a voltage is applied with a voltage, an ink drop is issued. The opposing electrodes are applied with a voltage in a time-division manner.

Abstract: An ink-jet printer wherein a pair of horizontal deflection electrodes and a pair of vertical deflection electrodes are disposed in the order named in the direction of travel of ink drops so that the charged ink drops may be deflected in the horizontal direction depending upon the charge on the respective ink drops, but the vertical deflection electrodes are so arranged or shaped or applied with such deflection voltage that the charged ink drops may be deflected in the vertical direction by the same amount, regardless of the charge on the respective ink drops, away from the trajectory of the uncharged ink drops, whereby the ink dots may be aligned along a horizontal line.

Abstract: Prior to printing, ink drops are ejected from an ink ejection head or nozzle (28) and an amount of deflection is sweepingly varied until the ink drops hit a target (57), thereby providing a reference which compensates for variations in an amount of charge of the ink drops, a mass of the ink drops, a deflection voltage and an ink drop velocity.

Abstract: Prior to printing, ink drops are ejected from an ink ejection head or nozzle (28) and an amount of deflection is sweepingly varied until the ink drops hit a target (57), thereby providing a reference which compensates for variations in an amount of charge of the ink drops, a deflection voltage and an ink drop velocity. The ink is caused to fall in drops from a container (48) having a predetermined volume and the number of drops per unit time, corresponding to the ink viscosity, is counted. The temperature of the ink is raised when the number of drops is below a predetermined number and vice-versa.